Designing & Testing Solid Core Bushings for Long Service Life by Armando Pastore & Laura De Fina

Bushings play a major influence in reliability of transformers and require good thermal dissipation behavior, reliable internal and external electrical insulation and adequate mechanical strength. The main technologies for internal insulation are oil-impregnated paper (OIP), resin-impregnated paper (RIP), resin-impregnated synthetic (RIS) and SF6, each offering relative advantages and disadvantages. All technologies are characterized by very high reliability based on service and manufacturing experience. This presentation discusses the findings of recent R&D work aimed at demonstrating suitable design criteria to ensure long service life of dry RIP bushings, where growing market demand relates to their safety aspects.